import java.util.Scanner;

public class Work08 {
    static int count = 0;
    static boolean isUsed[];

    static void dfs(int start,int end){
        if(start == 2){
            count++;
            return;
        }
        for (int i = 0; i < end; i++) {
            if(!isUsed[i]){
                isUsed[i] = true;
                dfs(start +1 ,end);
                isUsed[i] = false;
            }
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        isUsed = new boolean[n];
        for (int i = 0; i < 20; i++) {
            count = 0;
            dfs(0,i);
            if(count >= n){
                System.out.println(i);
                break;
            }
        }
    }
}
